<template>
  <div class="slide-verify" :style="{width: w + 'px'}" id="slideVerify" onselectstart="return false;">
    <!-- 图片加载遮蔽罩 -->
    <div :class="{'slider-verify-loading': loadBlock}"></div>
    <canvas :width="w" :height="h" ref="canvas" ></canvas>
    <div v-if="show" @click="refresh" class="slide-verify-refresh-icon"></div>
    <canvas :width="w" :height="h" ref="block"  class="slide-verify-block"></canvas>
    <!-- container -->
    <div class="slide-verify-slider" :class="{'container-active': containerActive, 'container-success': containerSuccess, 'container-fail': containerFail}">
      <div class="slide-verify-slider-mask" :style="{width: sliderMaskWidth}">
        <!-- slider -->
        <div @mousedown="sliderDown"
             @touchstart="touchStartEvent"
             @touchmove="touchMoveEvent"
             @touchend="touchEndEvent"
             class="slide-verify-slider-mask-item"
             :style="{left: sliderLeft}">
          <div class="slide-verify-slider-mask-item-icon"></div>
        </div>
      </div>
      <span class="slide-verify-slider-text">{{sliderText}}</span>
    </div>
  </div>
</template>
<script>
const PI = Math.PI;

function sum(x, y) {
  return x + y
}

function square(x) {
  return x * x
}
export default {
  name: 'SlideVerify',
  props: {
    // block length
    l: {
      type: Number,
      default: 42,
    },
    // block radius
    r: {
      type: Number,
      default: 10,
    },
    // canvas width
    w: {
      type: Number,
      default: 310,
    },
    // canvas height
    h: {
      type: Number,
      default: 155,
    },
    sliderText: {
      type: String,
      default: 'Slide filled right',
    },
    accuracy: {
      type: Number,
      default: 5, // 若为 -1 则不进行机器判断
    },
    show: {
      type: Boolean,
      default: true,
    },
    imgs: {
      type: Array,
      default: () => [],
    },
  },
  data() {
    return {
      containerActive: false, // container active class
      containerSuccess: false, // container success class
      containerFail: false, // container fail class
      canvasCtx: null,
      blockCtx: null,
      block: null,
      block_x: undefined, // container random position
      block_y: undefined,
      L: this.l + this.r * 2 + 3, // block real lenght
      img: undefined,
      originX: undefined,
      originY: undefined,
      isMouseDown: false,
      trail: [],
      sliderLeft: 0, // block right offset
      sliderMaskWidth: 0, // mask width,
      success: false, // Bug Fixes 修复了验证成功后还能滑动
      loadBlock: true, // Features 图片加载提示，防止图片没加载完就开始验证
      timestamp: null,
    }
  },
  mounted() {
    this.init()
  },
  methods: {
    init() {
      this.initDom()
      this.initImg()
      this.bindEvents()
    },
    initDom() {
      this.block = this.$refs.block;
      this.canvasCtx = this.$refs.canvas.getContext('2d')
      this.blockCtx = this.block.getContext('2d')
    },
    initImg() {
      const img = this.createImg(() => {
        // 图片加载完关闭遮蔽罩
        this.loadBlock = false;
        this.drawBlock()
        this.canvasCtx.drawImage(img, 0, 0, this.w, this.h)
        this.blockCtx.drawImage(img, 0, 0, this.w, this.h)
        let {
          block_x: x,
          block_y: y,
          r,
          L
        } = this
        let _y = y - r * 2 - 1
        let ImageData = this.blockCtx.getImageData(x, _y, L, L);
        this.block.width = L;
        this.blockCtx.putImageData(ImageData, 0, _y)
      });
      this.img = img;
    },
    drawBlock() {
      this.block_x = this.getRandomNumberByRange(this.L + 10, this.w - (this.L + 10))
      this.block_y = this.getRandomNumberByRange(10 + this.r * 2, this.h - (this.L + 10))
      this.draw(this.canvasCtx, this.block_x, this.block_y, 'fill')
      this.draw(this.blockCtx, this.block_x, this.block_y, 'clip')
    },
    draw(ctx, x, y, operation) {
      let {
        l,
        r
      } = this;
      ctx.beginPath()
      ctx.moveTo(x, y)
      ctx.arc(x + l / 2, y - r + 2, r, 0.72 * PI, 2.26 * PI)
      ctx.lineTo(x + l, y)
      ctx.arc(x + l + r - 2, y + l / 2, r, 1.21 * PI, 2.78 * PI)
      ctx.lineTo(x + l, y + l)
      ctx.lineTo(x, y + l)
      ctx.arc(x + r - 2, y + l / 2, r + 0.4, 2.76 * PI, 1.24 * PI, true)
      ctx.lineTo(x, y)
      ctx.lineWidth = 2
      ctx.fillStyle = 'rgba(255, 255, 255, 0.7)'
      ctx.strokeStyle = 'rgba(255, 255, 255, 0.7)'
      ctx.stroke()
      ctx[operation]()
      // Bug Fixes 修复了火狐和ie显示问题
      ctx.globalCompositeOperation = "destination-over"
    },
    createImg(onload) {
      const img = document.createElement('img');
      img.crossOrigin = "Anonymous";
      img.onload = onload;
      img.onerror = () => {
        img.src = this.getRandomImg()
      }
      img.src = require("../../assets/img/tab1.jpg")
      return img;
    },
    // 随机生成img src
    getRandomImg() {
      // return require('../assets/img.jpg')
      const len = this.imgs.length;
      return len > 0 ?
          this.imgs[this.getRandomNumberByRange(0, len)] :
          'https://picsum.photos/300/150/?image=' + this.getRandomNumberByRange(0, 1084);
    },
    getRandomNumberByRange(start, end) {
      return Math.round(Math.random() * (end - start) + start)
    },
    refresh() {
      this.reset()
      this.$emit('refresh')
    },
    sliderDown(event) {
      if (this.success) return;
      this.originX = event.clientX;
      this.originY = event.clientY;
      this.isMouseDown = true;
      this.timestamp = + new Date();
    },
    touchStartEvent(e) {
      if (this.success) return;
      this.originX = e.changedTouches[0].pageX;
      this.originY = e.changedTouches[0].pageY;
      this.isMouseDown = true;
      this.timestamp = + new Date();
    },
    bindEvents() {
      document.addEventListener('mousemove', (e) => {
        if (!this.isMouseDown) return false;
        const moveX = e.clientX - this.originX;
        const moveY = e.clientY - this.originY;
        if (moveX < 0 || moveX + 38 >= this.w) return false;
        this.sliderLeft = moveX + 'px';
        let blockLeft = (this.w - 40 - 20) / (this.w - 40) * moveX;
        this.block.style.left = blockLeft + 'px';

        this.containerActive = true; // add active
        this.sliderMaskWidth = moveX + 'px';
        this.trail.push(moveY);
      });
      document.addEventListener('mouseup', (e) => {
        if (!this.isMouseDown) return false
        this.isMouseDown = false
        if (e.clientX === this.originX) return false;
        this.containerActive = false; // remove active
        this.timestamp = + new Date() - this.timestamp;

        const {
          spliced,
          TuringTest
        } = this.verify();
        if (spliced) {
          if(this.accuracy === -1) {
            this.containerSuccess = true;
            this.success = true;
            this.$emit('success', this.timestamp);
            return;
          }
          if (TuringTest) {
            // succ
            this.containerSuccess = true;
            this.success = true;
            this.$emit('success', this.timestamp)
          } else {
            this.containerFail = true;
            this.$emit('again')
          }
        } else {
          this.containerFail = true;
          this.$emit('fail')
          setTimeout(() => {
            this.reset()
          }, 1000)
        }
      })
    },
    touchMoveEvent(e) {
      if (!this.isMouseDown) return false;
      const moveX = e.changedTouches[0].pageX - this.originX;
      const moveY = e.changedTouches[0].pageY - this.originY;
      if (moveX < 0 || moveX + 38 >= this.w) return false;
      this.sliderLeft = moveX + 'px';
      let blockLeft = (this.w - 40 - 20) / (this.w - 40) * moveX;
      this.block.style.left = blockLeft + 'px';

      this.containerActive = true;
      this.sliderMaskWidth = moveX + 'px';
      this.trail.push(moveY);
    },
    touchEndEvent(e) {
      if (!this.isMouseDown) return false
      this.isMouseDown = false
      if (e.changedTouches[0].pageX === this.originX) return false;
      this.containerActive = false;
      this.timestamp = + new Date() - this.timestamp;

      const {
        spliced,
        TuringTest
      } = this.verify();
      if (spliced) {
        if(this.accuracy === -1) {
          this.containerSuccess = true;
          this.success = true;
          this.$emit('success', this.timestamp);
          return;
        }
        if (TuringTest) {
          // succ
          this.containerSuccess = true;
          this.success = true;
          this.$emit('success', this.timestamp)
        } else {
          this.containerFail = true;
          this.$emit('again')
        }
      } else {
        this.containerFail = true;
        this.$emit('fail')
        setTimeout(() => {
          this.reset()
        }, 1000)
      }
    },
    verify() {
      const arr = this.trail // drag y move distance
      const average = arr.reduce(sum) / arr.length // average
      const deviations = arr.map(x => x - average) // deviation array
      const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length) // standard deviation
      const left = parseInt(this.block.style.left)
      const accuracy = this.accuracy <= 1 ? 1 : this.accuracy > 10 ? 10 : this.accuracy;
      return {
        spliced: Math.abs(left - this.block_x) <= accuracy,
        TuringTest: average !== stddev, // equal => not person operate
      }
    },
    reset() {
      this.success = false;
      this.containerActive = false;
      this.containerSuccess = false;
      this.containerFail = false;
      this.sliderLeft = 0;
      this.block.style.left = 0;
      this.sliderMaskWidth = 0;
      // canvas
      let {
        w,
        h
      } = this;
      this.canvasCtx.clearRect(0, 0, w, h)
      this.blockCtx.clearRect(0, 0, w, h)
      this.block.width = w

      // generate img
      this.img.src = this.getRandomImg();
      this.$emit('fulfilled')
    },
  }
}
</script>
<style scoped>
.slide-verify {
  position: relative;
}

/* 图片加载样式 */
.slider-verify-loading{
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  bottom: 0;
  background: rgba(255, 255, 255, 0.9);
  z-index: 999;
  animation: loading 1.5s infinite;
}

@keyframes loading {
  0%{
    opacity: .7;
  }
  100% {
    opacity: 9;
  }
}

.slide-verify-block {
  position: absolute;
  left: 0;
  top: 0
}

.slide-verify-refresh-icon {
  position: absolute;
  right: 0;
  top: 0;
  width: 34px;
  height: 34px;
  cursor: pointer;
  background: url("./assets/icon_light.png") 0 -437px;
  background-size: 34px 471px
}

.slide-verify-slider {
  position: relative;
  text-align: center;
  width: 100%;
  height: 40px;
  line-height: 40px;
  margin-top: 15px;
  background: #f7f9fa;
  color: #45494c;
  border: 1px solid #e4e7eb
}

.slide-verify-slider-mask {
  position: absolute;
  left: 0;
  top: 0;
  height: 40px;
  border: 0 solid #1991FA;
  background: #D1E9FE
}

.slide-verify-slider-mask-item {
  position: absolute;
  top: 0;
  left: 0;
  width: 40px;
  height: 40px;
  background: #fff;
  box-shadow: 0 0 3px rgba(0, 0, 0, 0.3);
  cursor: pointer;
  transition: background .2s linear
}

.slide-verify-slider-mask-item:hover {
  background: #1991FA
}

.slide-verify-slider-mask-item:hover .slide-verify-slider-mask-item-icon {
  background-position: 0 -13px
}

.slide-verify-slider-mask-item-icon {
  position: absolute;
  top: 15px;
  left: 13px;
  width: 14px;
  height: 12px;
  background: url("./assets/icon_light.png") 0 -26px;
  background-size: 34px 471px
}
.container-active .slide-verify-slider-mask-item {
  height: 38px;
  top: -1px;
  border: 1px solid #1991FA;
}

.container-active .slide-verify-slider-mask {
  height: 38px;
  border-width: 1px;
}

.container-success .slide-verify-slider-mask-item {
  height: 38px;
  top: -1px;
  border: 1px solid #52CCBA;
  background-color: #52CCBA !important;
}

.container-success .slide-verify-slider-mask {
  height: 38px;
  border: 1px solid #52CCBA;
  background-color: #D2F4EF;
}

.container-success .slide-verify-slider-mask-item-icon {
  background-position: 0 0 !important;
}

.container-fail .slide-verify-slider-mask-item {
  height: 38px;
  top: -1px;
  border: 1px solid #f57a7a;
  background-color: #f57a7a !important;
}

.container-fail .slide-verify-slider-mask {
  height: 38px;
  border: 1px solid #f57a7a;
  background-color: #fce1e1;
}

.container-fail .slide-verify-slider-mask-item-icon {
  top: 14px;
  background-position: 0 -82px !important;
}

.container-active .slide-verify-slider-text,
.container-success .slide-verify-slider-text,
.container-fail .slide-verify-slider-text {
  display: none;
}
</style>

